The present invention relates to a novel tape cassette, and more particularly to a tape cassette including a cassette case, a tape reel rotatably accommodated in the cassette case, a recording medium tape wound around the tape reel, and a reel lock member slidably over an internal surface in the cassette case for locking the tape reel, wherein the internal surface (hereinafter "slide surface") of the cassette case with which the reel lock is in sliding contact is improved to ensure this smooth sliding of the reel lock member with respect to the cassette case, and locking and unlocking of the reel lock member with respect to the tape reel is reliably effected.
In a tape cassette for use with a VTR or the like, there is provided a reel lock mechanism for preventing slack of a tape when the tape cassette is in an unused condition.
FIGS. 7 and 8 show an example of such a reel lock mechanism a in a the conventional tape cassette in which Reference characters b designates a lower half of a cassette case, and reference characters e and c' designate lower flanges of a supply tape reel and a take-up tape reel around which a magnetic tape d is wound. The lower flanges c and c' are formed with a plurality of outer circumferential teeth e and e', respectively.
Reference character f designates a reel lock member comprised of a main portion g and two lock portions h and h' projecting from the main portion g. The reel lock member f is biased in a direction depicted by an arrow A by a spring or other biasing means (not shown).
The lock portions h and h' are formed of an elastic material, and they are normally engaged with the teeth e and e' of the lower flanges c and c' to thereby lock the tape reels against rotation in tape-loosening directions.
In other words, while the flanges c and c' are permitted to rotate in opposite directions indicated by arrows B and B', the flanges c and c' are restrained from rotating in the directions to create slack in the magnetic tape d by means of the lock portions h and h'.
In the reel lock mechanism of the tape cassette mentioned above, when the tape cassette is loaded into a cassette receiving portion of a recording and reproducing apparatus, the locked condition of the tape reels has to be released. Therefore, a slide surface of the lower half b, on which the reel lock member f is adapted to slide, is formed with a through-hole i for allowing insertion of a lock release pin j provided in the cassette receiving portion. Further, the main portion g of the reel lock member f is formed at its lower surface with an engagement hole k for receiving the lock release pin j inserted through the through-hole i of the lower half b. When the lock release pin j is engaged with the engagement hole k of the reel lock member f, the lock release pin j is moved in an unlocking direction, that is, in the direction depicted by an arrow C in FIG. 8, thereby moving the reel lock member f in the unlocking direction against a biasing force of the biasing means.
There is a possibility that a burr is generated at an opening edge of the through-hole i upon formation of the through-hole i through the slide surface of the lower half b. As a result, a bottom surface of the main portion g of the reel lock member f may be caught by such burr during the movement of the reel lock member f. Thus, smooth sliding movement of the reel lock member f is hindered. Particularly, the movement in the locking direction may be hindered to cause defective locking.
Further, the lower half b is formed with a complicated arrangement of many walls and projections in the area where the reel lock member f is disposed. Therefore, in molding the cassette case, an ejector pin is employed to abut against the slide surface of the lower half b, so as to separate the lower bali b from the mold. In this case, a burr-like projection is often generated at the peripheral edge of an area of contact of the ejector pin with the slide surface. Such burr-like projection also hinders the smooth sliding movement of the reel lock member f.
Although the burr generated at the opening edge of the through-hole i or the burr-like projection generated at the peripheral edge of the area of contact of the ejector pin with the slide surface may be removed by a finishing process carried out after molding of the cassette case smoothen the slide surface of the lower half b, this method is undesirable since such an finishing process causes a great increase in cost.